Field of the Invention
The present invention relates to a technique for identifying an object in a background and a moving object relating to a gesture operation or the like based on distance information.
Description of the Related Art
A system for performing an operation on an object displayed or placed on a board such as a white board and a table using a user interface (UI) that allows input by a gesture has been proposed. In such a system, it is preferable that, in a two-dimensional space parallel to the board, a difference between an operation area where the system can recognize an operation by a gesture, a touch, or the like, and the size and shape of the board is small. In other words, it is expected that an operation can be performed in almost all of the board area.
In the above-mentioned system, in many cases, in a state where a flat part of a predetermined board faces from the front, an image including the board within an angle of view is captured, and from the captured image, an object moving above the board is detected to recognize an operation performed by the object. In an area where a fixed board is included in a background, using known background subtraction, the area including the object above the board can be easily extracted. In an area (if the board is a table, the periphery of the table) not including the board in the background, however, as compared to the area above the board, positions and the number of objects existing in the background are unstable. Consequently, it is not always appropriate to use the background subtraction similarly to the detection of objects above the board.
Japanese Patent Application Laid-Open No. 2007-64894 discusses, in processing for detecting an object from an image, to use different object detection methods for respective partial areas depending on predetermined factors.
In a system in which an operation area and a predetermined board have different size and shape, the object detection is to be performed both in an area (above the board) including the board in a background, and in an area not including the board in the background. In the known technique, the detection of an object existing over two areas of different background conditions is not fully considered.